The F-5s were initially purchased in the 1970s by the Air Force and then sold through foreign military sales to Switzerland. In 2002, the Department of Defense decided to repatriate many of these aircraft back to the Navy. The F-5 is a twin-engine tactical fighter aircraft that provides air-to-air combat training for Navy and Marine Corps pilots. Its reliability and low operating costs result in savings to the Navy each year in maintenance and unnecessary wear on current strike fighter aircraft like the F/A-18 Super Hornet and F-35 Lightning II without sacrificing essential pilot training in a formidable aircraft.

In 2019, the depot-level maintenance and repair of the F-5 airframe transitioned from the original equipment manufacturer to organic support, and FRCSE was designated as the U.S. Navy depot source of repair. Currently, FRCSE performs Phased Depot Maintenance (PDM). This process includes replacing certain high time structural and system components and thoroughly inspecting the aircraft in known corrosion and metal fatigue areas. Artisans use various means, including non-destructive inspection (NDI) methods to look for corrosion and/or cracks caused by wear and stress fatigue.

“The maintenance we conduct at the depot extends the service life of the aircraft, as each phase of the PDM addresses time-limited component inspections and replacements at certain flight hours,” said Cris Baldwin, FRCSE’s F-5 Production Line Director.

Planned structural component replacements include the upper cockpit longeron (UCL) and the vertical stabilizer (V-stab). The UCLs, approximately six-foot beams that run down either side of the cockpit, are the main structural components of the airframe and provide fundamental rigidity to the aircraft around the cockpit. The V-stab, another critical component, is the static part of the vertical tail that stabilizes and balances the aircraft in yaw. These load-bearing sections of the aircraft are replaced at regular intervals, but before recent process innovations, the work was not able to be done concurrently.

“One of the innovative time reduction efforts was the idea to perform the UCL and V stab work concurrently,” said Lt. Cmdr. Ryan McNulty, FRCSE’s F-5 Production Line Military Director. “Originally, these were done separately because each is a critical structural element. With one or the other removed, there is a risk that the airframe could be permanently damaged due to twisting. Fortunately, we have an in-house engineering support team and a dynamic manufacturing division that provided sound, innovative thinking in an effort to conduct these efforts concurrently.”

Concurrent work would significantly reduce the time needed to return the aircraft back to adversary operations, but the team faced risks associated with the stability of the aircraft. To conduct the UCL and V stab repairs simultaneously, the airframe had to be adequately supported.  FRCSE’s engineering and manufacturing teams designed robust shoring to sit beneath the aircraft and prevent twisting, which illustrates the level of ongoing innovation at the depot.

“The F-5 engineering team devised and performed a test to determine if and how much the airframe would flex when the UCL and V stab work was performed at the same time,” McNulty said. “The results proved that by using the shoring, the two repairs could be performed together.”

While the concurrent work for UCLs and V stabs are the most beneficial of the F-5 production line efforts to reduce the time the aircraft is at the depot, they are far from the only ones. There have been more than 45 innovative solutions proposed to help turn aircraft around faster. More than half of those solutions came from artisans on the production floor, and include V stab work stands, flight control rigging tool test kits, and a mobile, hand-held, E-drill® system to remove hard metal fasteners more than 20 times faster than twist drills. These technological advancements should provide increased productivity as the team continues to get more adept.

“The F-5 team is an amazing group of professionals with many challenges to overcome to meet the Fleet’s demand,” said Baldwin. “Over the last year, I have seen incredible improvements, and I know this line will soon become the best-performing product line at FRCSE. I’m proud of their performance and continued dedication to the warfighter.”